Exam 1

Question 1

Sound requires a ______ to pass through.

Answer 1

medium

(could be air, water, solids…but CANNOT travel in a vacuum like space)

Question 2

Brownian motion

Answer 2

Random high-speed movement of molecules due to their inherent energy; describes movement of air molecules.

Question 3

How is sound generated?

Answer 3

By air molecules set in motion or changes in air pressure.

Question 4

Dyne

Answer 4

Unit of measurement of air pressure used for small amounts of froce over small areas.

Example: eardrum

Question 5

Pounds per square inch (psi)

Answer 5

Unit of measurement of air presure used for larger amounts of force over larger areas.

Question 6

Metric measurements of air pressure

Answer 6

More current system:

• MKS (bigger units)
  
  • Distance (meters), mass (kilogram), and time (second)
  • Pressure measured in Newtons per square meter (=1 pascal)
• cgs (smaller units)
  
  • Distance (centimeter), mass (gram), and time (seconds)
  • Pressure measured in dynes per square cm (=1 microbar)

Question 7

What is the atmospheric pressure at sea level?

Answer 7

14.7 P_atmos

(Positive pressure is greater than P_atmos; negative pressure is lesss than P_atmos

Question 8

Air moves from areas of ____ to ____ pressure.

Answer 8

high to low

Question 9

Volume velocity

Answer 9

Refers to the speed of a volume of air traveling in a certain direction.

Question 10

Driving pressure

Answer 10

The difference between high- and low-pressure areas that causes air to flow between these areas.

Question 11

Laminar airflow

Answer 11

Smooth airflow with molecules moving in a parallel manner and at the same speed.

Question 12

Turbulent airflow

Answer 12

An obstacle distrubs airflow, causing eddies which result in random variations in the pressure of the air.

Question 13

Volume

Answer 13

The amount of space occupied in 3 dimensions.

Question 14

Density

Answer 14

The amount of mass per unit of volume.

Question 15

Boyle’s law

Answer 15

As the volume of a particular enclosed space increases, the pressure of the air within that space decreases; as the volume of the enclosed space decreases, the pressure of the air increases (if temperature remains constant).

Question 16

There is a ____________ relationship between air pressure & density.

Answer 16

proportional

Question 17

Compression

Answer 17

Area in a sound wave where molecules approach and collide, resulting in increased density and increased pressure.

Question 18

Rarefaction

Answer 18

Area in a sound wave where distance between molecules increases, resulting in decreased density and decreased pressure.

Question 19

Speed

Answer 19

Describes the relationship between distance and time, e.g. 60 miles per hour

Question 20

Velocity

Answer 20

Gives you the same information as speed (distance/time), but includes direction.

Question 21

Acceleration

Answer 21

Change in velocity over time.

Question 22

Newton’s first law of motion

Answer 22

A moving object will continue moving in a straight line at a constant speed and stationary object will remain at rest, unless acted upon by an outside force

Question 23

Newton’s second law of motion

Answer 23

The net force of an object is equal to its mass times its acceleration and points in the direction of the acceleration.
Net force = mass times acceleration (F = ma).

Question 24

Newton’s third law of motion

Answer 24

For every action (force) there is an equal and opposite reaction (force)

Question 25

Elasticity

Answer 25

Restoring force that brings an object back to its original size, shape, or position after having been displaced or deformed.

Question 26

Inertia

Answer 26

The tendency of matter to remain at rest or in motion unless acted on by an outside force.

Question 27

Hooke’s Law

Answer 27

States that the restoring force (elasticity) is proportional to the distance of displacement and acts in the opposite direction. Thus, the farther an object is displaced from its origional location, the stronger the restoring force that pulls it back toward that position.

Question 28

Amplitude

Answer 28

The amount of displacement of an object from its rest position.

Question 29

Damping

Answer 29

A decrease in amplitude.

Question 30

What do logarithms tell you?

Answer 30

Tells how many of one number we multiply to get another number.

y = b^x is the same as log_b(y) = x

Question 31

What does a logarithm without a base mean?

Answer 31

The base is 10. Represents the # of times you need to use 10 in a multiplication to get the desired number.

log(1000) = log₁₀(1000)** = 3**

Question 32

Linear vs. logarithmic scales

Answer 32

• Linear: units are the same distance from one another
  
  • can be added/subtracted
  • ex: ruler
• Logarithmic: units increase by greater and greater amounts as you go up the scale
  
  • cannot be added/subtracted
  • has a base (ex: 10) raised to some power
  • ex: decibel scale

Question 33

Ratio scale

Answer 33

A scale that reflects a relationship between quantities. The decibel scale is a ratio scale that measures the relationships between the amplitudes or the intensities of two sounds (the target sound and the standard reference sound).

Question 34

Threshold of hearing

Answer 34

Sound that a pair of normal human ears can detect 50% of the time under ideal listening conditions. This is the standard reference sound.

0 dB

Question 35

Threshold of pain

Answer 35

Intensity level of 130 dB, which causes a sensation of pain in the ears.